Question

I would like to use an annotation on a key string to configure the initial value for a property of that key. E.g.,

@NodeProperty(initialValue = "bar") static final String "FOO";

Other code later processes the annotation, adding a key “FOO” with value “bar” to a particular key-value store, if key “FOO” doesn’t already exist.

My annotation declaration is:

@Retention(RetentionPolicy.RUNTIME)
@interface NodeProperty {
    long initialValue();  // I want to accept Strings, ints, byte[], etc. here.
}

But, I don’t know the type of initialValue ahead of time. I’d like to accept all primitives, Strings, and arrays of the these.

Any ideas on how to accomplish this?

Edit:

Unfortunately, it sounds like overloading the annotation parameter isn’t currently possible. The answers below contain various workarounds.

Answer 1

Accept a single type (likely String) and use type conversion to get it from what-you-got to what-the-field-is. Similar to how Commons BeanUtils or XWork allow registering type converters to get from string form values to arbitrary Java classes.